1. Field of the Invention
Embodiments of the invention relate to semiconductor devices such as power semiconductor modules (hereinafter, simply referred to as a power modules), where a plurality of semiconductor chips are contained in the same package.
2. Related Art
FIG. 14 is a schematic cross-sectional diagram illustrating a power module in the related art. As illustrated in FIG. 14, a package 501 of a power module 500 is configured to include a metal base 51, an insulating substrate 52, a main terminal 55 and a control terminal 56 which are attached to a circuit pattern 52a of the insulating substrate 52, and a resin case 57. In the power module 500, a semiconductor chip 54 including semiconductor elements is attached on the insulating substrate 52 of the package 501.
In the insulating substrate 52, the circuit pattern 52a is installed on the front-surface side of an insulating layer 52b, and a rear copper foil 52c is installed on the rear-surface side thereof. The front surface of the metal base 51 is attached to the rear copper foil 52c of the insulating substrate 52 through solder (not illustrated). The rear surface of the semiconductor chip 54, one end of the main terminal 55, and one end of the control terminal 56 are attached to the circuit pattern 52a of the insulating substrate 52 through solder (not illustrated).
Electrodes of the semiconductor elements (not illustrated) installed on the front surface of the semiconductor chip 54 and the circuit patterns 52a are electrically connected to each other through bonding wires 60, and the circuit patterns 52a are electrically connected to each other through bonding wires 60. A resin case 57 is adhered to a circumference of the metal base 51 so as to cover the front-surface side of the metal base 51. The resin case 57 is configured so that a sidewall 58 and cover 59 are integrally formed. Each of the other ends of the main terminal 55 and the control terminal 56 penetrates the cover 59 of the resin case 57 to be exposed to an outer side of the resin case 57.
Next, a configuration of a vicinity M of the control terminal 56 of the power module 500 will be described in detail. FIG. 15 is a cross-sectional diagram illustrating main components in a vicinity of the control terminal of the power module illustrated in FIG. 14. In FIG. 15, the insulating substrate 52 configured to include the circuit pattern 52a, the insulating layer 52b, and the rear copper foil 52c are simplified in the illustration. The control terminal 56 is formed so as to be integrated with a control terminal block 61. The control terminal block 61 is fit into the resin case 57.
The control terminal 56 has a bent portion T at the portion which is closer to the insulating substrate 22 than the control terminal block 61 integrated with the control terminal 56. The control terminal 56 functions as a spring due to elasticity of the bent portion T to press down the insulating substrate 52, so that the control terminal 56 secures a conduction state with respect to the circuit pattern 52a of the insulating substrate 52. The end portion of the control terminal 56, which is exposed to the outer side of the resin case 57, is connected to an external wire line through a connector (not illustrated).
At the time of attachment/detachment of the connector, a stress is exerted on the control terminal 56 in the direction facing the insulating substrate 52 or in the direction being separated from the insulating substrate 52. Therefore, at the time of attachment of the connector, the stress is exerted on the control terminal 56 in the direction facing the insulating substrate 52. However, since the control terminal 56 is fit into the resin case 57 through the control terminal block 61, the stress exerted on the control terminal 56 is prevented from being transferred to the insulating substrate 52 through the control terminal 56. Accordingly, no stress is exerted on the insulating substrate 52.
As a power module where the control terminal and the control terminal block are integrally formed and the control terminal block is fit into the resin case in this manner, the following apparatus is proposed. Lead pins of signal terminals are retained in a signal terminal block, and the signal terminal block is retained in an outer case. The lead pin has a bent portion between the portion where the lead pin is retained and the distal end portion thereof in the package. When the outer case is mounted on a metal base plate, the lead pin of which the free length (before compression) is set to be longer than the compressed length is compressed so as to press the circuit substrate (for example, refer to Patent Literature 1 listed below).
FIGS. 16(a) and 16(b) are cross-sectional diagrams illustrating main components of a power module in another example of the related art. The power module 600 illustrated in FIGS. 16(a) and 16(b) is different from the power module 500 illustrated in FIG. 14 in terms of a configuration of a vicinity M of control terminal 56. FIG. 16(a) illustrates a cross-sectional diagram of main components in the vicinity M of the control terminal 56 of the power module 600. FIG. 16(b) illustrates a cross-sectional diagram of the main components as the vicinity M of the control terminal 56 illustrated in FIG. 16(a) is seen from the side of the sidewall 58 of the resin case 57 (in the direction indicated by a white leftward arrow N).
As illustrated in FIGS. 16(a) and 16(b), the front surface of the metal base 51 is attached to the rear copper foil 52c of the insulating substrate 52 through solder 53. The control terminal 56 is configured to include a penetration portion 56a which penetrates a penetration hole 59a of a cover 59 of the resin case 57, an L-shaped processed portion 56b which is connected to an end of the penetration portion 56a to constitute an L-shaped cross section together with the penetration portion 56a, and a connection portion 56c of which the one end is connected to the L-shaped processed portion 56b and of which the other end is fixed to the insulating substrate 52 by soldering. The other end of the connection portion 56c is perpendicularly bent, and the perpendicularly-bent end of the connection portion 56c is attached to the insulating substrate 52 through solder 62.
The end of the penetration portion 56a opposite to the end of the penetration portion 56a, which is connected to the L-shaped processed portion 56b, is exposed to the outer side of the resin case 57. A protrusion portion 63 which is in contact with the rear surface 59c of the cover 59 of the resin case 57 after the completion of assembly of the power module 600 is installed in the portion of the penetration portion 56a, which penetrates the resin case 57. Since the protrusion portion 63 is in contact with the rear surface 59c of the cover 59 of the resin case 57, the control terminal 56 is not pulled out in the direction from the resin case 57 to the outer side (in the direction indicated by a white upward arrow P of FIG. 16(b)).
An external wire line is connected to the end of the penetration portion 56a of the control terminal 56, which is exposed to the outer side of the resin case 57, through the connector 64. Although not illustrated in FIGS. 16(a) and 16(b), the penetration portion 56a of the control terminal 56 is connected into a socket 64a of the connector 64. In the case of detaching the connector 64 from the penetration portion 56a of the control terminal 56, a stress is exerted on the control terminal 56 in the direction P being separated from the insulating substrate 52 (in the direction indicated by a white upward arrow P).
Because the protrusion portion 63 formed in the control terminal 56 is in contact with the rear surface 59c of the cover 59 of the resin case 57, the stress exerted on the control terminal 56 in the direction P being separated from the insulating substrate 56 may be prevented. Therefore, in the case of detaching the connector 64 from the penetration portion 56a of the control terminal 56, the stress exerted on the control terminal 56 is not transferred to the insulating substrate 56 through the control terminal 56.
As a power module having the configuration where no stress is exerted on the insulating substrate at the time of detaching the connector from the control terminal in this manner, the following apparatus is proposed. A spring is installed in the end of the control terminal, which is closer to the insulating substrate, and the control terminal is in contact with the insulating substrate by compressing the spring. Alternatively, a member having the same operation as a spring is installed in the end of the control terminal, which is closer to the insulating substrate, and the control terminal is in contact with the insulating substrate by using the member. In addition, a hook is installed in the control terminal to prevent the control terminal from being moved in the direction being separated from the insulating substrate. On the other hand, as a power module having the configuration where no pressure is exerted on the insulating substrate through the control terminal at the time of attaching the connector to the control terminal, an apparatus where the portion of the control terminal, which is exposed to the outer side of the resin case, is allowed to be bent to be in contact with the surface of the resin case is proposed. For example, refer to US Patent Application Publication No. 2008/0217756 (also referred to herein as “Patent Literature 2”).
However, in the power module disclosed in Japanese Patent Publication No. JP 2000-208686 (also referred to herein as “Patent Literature 1”) and the power module 500 illustrated in FIGS. 14 and 15 described above, a process for integrally formed the control terminal 56 in the control terminal block 61 and a process for fitting the control terminal block 61 into the resin case 57 are required, so that production cost is increased.
In addition, in the power module 600 illustrated in FIGS. 16(a) and 16(b), at the time of attaching the connector 64, a stress is exerted on the control terminal 56 in the direction (white downward arrow) Q facing the insulating substrate 52. Therefore, at the time of attaching the connector 64, the stress exerted on the control terminal 56 is transferred to the insulating substrate 52 through the control terminal 56, so that the pressure is exerted on the insulating substrate 52. Accordingly, at the portion R corresponding to the control terminal 56 of the insulating substrate 52, the insulating substrate 52 is fractured, so that dielectric strength is decreased. Otherwise, the insulating substrate 52 is depressed, and thus, that the control terminal 56 is displaced, so that the solder 62 attaching the control terminal 56 and the insulating substrate 52 is damaged. Therefore, there is a problem in that the reliability of the power module 600 is deteriorated.
In addition, in the power module disclosed in Patent Literature 2 described above, in the case of attaching the connector to the control terminal, it is not disclosed that the pressure exerted on the insulating substrate through the control terminal is blocked by the protrusion portion installed in the control terminal. Therefore, in the case of attaching the connector to the control terminal, the pressure exerted on the insulating substrate cannot be suppressed.
Thus, there is a need in the art for an improved semiconductor device.